Apparatus, systems, and methods provide for the management of a high temperature electrolysis process. According to embodiments described herein, a fuel cell electrolyzer stack is utilized in an electrolysis process. One implementation includes the use of a solid oxide electrolyzer. Input voltage is cycled around a thermal neutral voltage such that the fuel cell electrolyzer stack cycles between operation in an exothermic mode and an endothermic mode. The waste heat generated by operation in the exothermic mode is used to support the endothermic operation. By cycling between operation modes, the temperature of the fuel cell electrolyzer stack may be controlled without the use of a cooling loop or recirculated reactant flow, and the efficiency of the electrolysis process is maximized.